Texas law says that a will must be probated within four years. This rule is found in Texas Estates Code § 256.003:
… a will may not be admitted to probate after the fourth anniversary of the testator’s death unless it is shown by proof that the applicant for the probate of the will was not in default in failing to present the will for probate on or before the fourth anniversary of the testator’s death.
While the will can be probated after this four year period, the courts will typically ask for some testimony. This is simply proof that the applicant was not in default in failing to present the will for probate within four years. Typically, this requires an explanation that the applicant did not know that probate was needed, that the will existed, etc.
When a will needs to be probated, the four year rule noted above is the standard. However, it does not mean that the person in possession of the original will can simply do nothing for four years.
Additionally, it is not a free pass for the person who has the original will to keep it a secret for four years.
Legally, person who has the original will is required to deliver the will to the clerk. This requirement is found in Texas Estates Code § 252.201. This rule is not tied to the four year period to probate the will. Delivering the will and probating the will are two entirely separate concepts.