Membership due change over time
This sounds like you want a Lifetime membership type with its minimum fee to level up every "x" years. Similar to purchasing a Gold - you can have it for lifetime but its price just increases with time.

If this is what you want, simply create a membership type from Administer -&gt; CiviMember -&gt; Membership Type with duration set to lifetime and write a custom code in extension/module which increases the minimum fee value of this membership type id with time in year.

Refererence for creating an extension - https://docs.civicrm.org/dev/en/master/extensions/civix/