从含义上讲：
become due(还可以表达为be due, fall due)，意思是"票据到期，期满应付"，如payments that become due即将到期的款项；而expire，侧重于所有权等权利到期失效，或任期届满，或期限终止结束。
从法律层面讲：
expire附带某种法律效力，较为正式，而due没有这样的效果。
1become due
except liens for taxes that not yet become due or payable and liens that arise in the ordinary course of business and do not materially impair such Company’s ownership or use of such property or assets.
尚未到期或应付的税款进行的留置以及在正常经营过程中产生的留置，且不会对该公司拥有或使用该等财产或资产产生重大影响的除外
2expire
In the event of a violation of my non-competition obligations hereunder, the term of the Period of Non-Competition shall be tolled effective the date of the first violation and shall commence to run only upon the grant of relief to the Company or any affiliate of the Company by a court of competent jurisdiction for all damages incurred by the Company or any affiliate of the Company, with the term of the Period of Non-Competition reduced only by the time between the date of the expiration or termination of this Letter of Commitment and the date of first violation by me.
本人违反本函项下的竞业禁止义务的，竞业禁止期将自首次违约日重新计算，并仅应在有合法管辖权的法院就公司或其任何关联方产生的所有损害，向公司或其任何关联方授予救济后开始生效。在此情况下，竞业禁止期将缩短一段时间，相当于自本承诺函到期或终止之日起至本人首次违约之日止的期间。
